Free piston machine



H. B. HORGEN FREE PISTON MACHINE Filed April 11, 1945 g o INVENTDR AATTORN E Y5 Patented Mar. 6, 1951 FREE PISTON MACHINE Helge BodvarHon-gen, Lyon, France, assignor, by direct and mesne assignments, ofnine-tenths to Raul Pateras Pescara, Lisbon, Portugal. and one-tenth toSociete dEtudcs et de Participations, Eau, Gaz, Electricite, Energie S.A. Geneva, Switzerland, a society of Switzerland Application April 11,1945, Serial No. 587,695 In France May 30, 1944 7 Claims. 1

The present invention relates to free piston machines, and especiallymotor compressors and auto generators of the free piston type, thesemachines including at least one movable system constituted by a motorpiston rigid with at least one compressor piston, the expressioncompressor piston designating", in this case, as well a piston servingfor the actual delivery of compressed gas as a piston coacting with acylinder containing a cushion of gas acting as an energy accumulator forensuring the return displacements of this movable system, or else apiston performing both of these functions.

The application of the present invention is particularly interesting inthe case of free piston 'machines, and especially auto generators, in

which the cylinder coacting with the compressor piston and the airreservoir for the feed of the motor cylinder are contiguous to eachother, discharge valves being provided in the wall that separates saidfirst mentioned cylinder from said reservoir.

The object of the present invention is to pro- ,vide a machineof thetype above set forth in which the movable system is better guided thanin machines made up to this time.

A preferred embodiment of my invention will be hereinafter described,with reference to the accompanying drawings, given merely by way ofexample, and in which:

Fig. 1 is a diagrammatic axial sectional view of a free piston autogenerator made according to the present invention; and

Figs. 2 to 4 show certain elements of the eccentric guiding means of thecompressor piston of said auto generator.

This auto generator includes a motor cylinder 1 surrounded by acasing 2acting as feed air reservoir for said cylinder. The wall of cylinder Iis provided with inlet ports 3 and outlet ports t. opened by pistons 5and 5' when said pistons are at the ends of the outward strokes.

Compressor pistons 6 and 6', of larger diameter than the correspondingmotor pistons, and adapted to coact with cylinders 1 respectively, arerigidly associated with each of said motor pistons. The combination of amotor piston and the corresponding compressor piston constitutes what iscalled, in the present specification, a movable system. The two movablesystems, symmetrical with respect to each other, of the auto generatorshown in the drawing have opposed movements and are interconnected bysynchronizin means, not shown by the drawing.

Each of the cylinders l is closed, on the outer side, by a cylinder head8, and on the inner side, by an annular partition 9.

The variable volume chambers formed, in cylinders 'l, on the outer sidesof the compressor pistons constitute energy accumulators for ensuringthe return strokes of the movable systems toward the center, owing tothe energy stored up in the air cushions present in these chambersduring the outward strokes of said movable systems.

The variable volume chambers formed, in cylinders l, on the inner sidesof the compressor pistons are fitted with inlet valves I2 and dischargevalves l3, these valves l3 being advantageously located in partitions 9in such manner as to feed the air compressed by pistons 66' into casing2, located between partitions 9. Com-- cally mounted rods 20, fixed inposition and parallel to the common axis of the cylinders, each of theserods extending with a snug fit through a slide member 2| provided in thecorresponding compressor piston of each movable system.

Preferably, said slide member 2i is mounted in such manner as to permita limited relative radial displacement thereof with respect to thecorresponding compressor piston 6-6, so as to make allowance for freeexpansion thereof. Furthermore, packing means are provided forpreventing leakage from one side to the other of the compressor piston.

For these purposes, in the embodiment illustrated in the drawings (Figs.2 to 4), slide member 2| is provided with two plane faces Zia, parallelto the axial plane of the corresponding piston 6-6 that passes half waybetween them, and adapted to coact with corresponding guiding surfaces33 rigid with said piston. The guiding surfaces 33 in question arecarried by a cap 34, the shape of which is shown by the perspective viewof Fig. 4, and which, under the efiect of tightening means, for instancescrews 34a engaged in a sleeve 36, applies the desired pressure on thepacking 35 of a stufiing box adapted to ensure a fiuidtight joint aroundtube 20. The

aeaassi in sleeve 36 fitted in piston 6-5.

Preferably, each rod 29 is fixed only at one end, to wit, the inner end,to the corresponding annular partitions a, and it extends sumciently faron the outer side for constantly guiding the compressor piston whateverbe the length of stroke thereof.

Advantageously, the two rods 20 of a, given machine, which may bedisposed in line with each other, are constituted by tubes open at bothends, the inner ends of these tubes being connected together through atube 20a located on the inside of casing 2. The whole of tubes 20 and20a thus constitutes a single conduit which permanently connectstogether the two energy accumulators located at the respective ends ofthe machine.

With such an arrangement, that is to say with a permanent communicationthus ensured between the two energy accumulators, a single startingdevice 22 is sufiicient for feeding starting air to the respective aircushion spaces of said accumulators. This starting device may beconnected to tube 20a, which is, in this case, provided with suitableports 23, inside casing 2, as shown in dotted lines by the drawing.

The machine shown by the drawing is fitted, in each cylinder 1, inaddition to the eccentric guiding rod 20, with a rod II located alongthe common axis of the cylinders and fixed to the end 8 of cylinder I.These rods II are slidably engaged with housings I provided on theinside of the corresponding movable system, axially with respectthereto. Each movable system includes, preferably close to its outerend, a seat slidable along the outer surface of rod II, so as thus toensure, in combination with eccentric rod 20, the axial guiding of saidend, while the inner end of said movable system is guided by the motorcylinder I.

Advantageously, a pivot joint, and preferably a ball and socket joint asshown at I4, is interposed between rod ii and the movable system whichincludes piston 6-6'. Owing to the presence of this joint, I eliminateany possibility of jamming or friction as might be caused bymisalignment of the axes of housing Ill and rod Ii.

Preferably, rod Ii is hollow and thus constitutes a tube. In this case,I may provide, at the free end of this tube, a stuiiing box I5, insidewhich is slidably mounted, in a fluid-tight manner, a sleeve it open atboth ends and assembled with the end of piston 6 or 5 in such mannerthat the inside of said sleeve communicates with a recess II provided onthe inside of said cylinder end. Furthermore, on the inside of tube IIis fixed a conduit i8 engaged with a suilicient annular clearance insleeve IS. The free open end of this conduit i8 is located, when thecorresponding piston is at the end of its outward stroke, close torecess I'I, so that, if a cooling liquid is injected through thisconduit I8, this liquid flows into recess II and then flows back throughsleeve I6 and tube I I, to be finally evacuated through a suitableoutlet passage I9.

Advantageously, a pivot joint is included in the means for axiallyguiding the motor piston. For this purpose, a portion of the outer wallof said piston is constituted by a cylindrical element 30 made of twohalves and the external cylindrical surface of which coacts with theinner cylindrical surface of the motor cylinder. The inner part of thiselement forms a hollow spherical surface 3| which engages acorresponding surface 32 provided on the motor piston. Surfaces 35-32constitute a ball and socket joint included in the motor piston axialguiding means. In order to facilitate assembly, each motor piston il-his made of three portions to, 5b and 5c. Portion Ida includes the pistonend and cavity ll. Portion 5c is directly attached to the correspondingcompressor piston, and portion 617 serves to connect portions 5a and Sotogether. The spherical surface 32 that carries cylindrical guidingelement 30 is formed on this intermediate portion Eb.

On the drawing, the machine has been shown as being symmetrical, butthis is not necessary.

What I claim is:

1. A free piston machine which comprises, in combination, a motorcylinder, two freely movable motor pistons adapted to work in opposeddirections in synchronism with each other in said cylinder, a compressorpiston rigid with each of said motor pistons on the outer side thereofand in coaxial relation therewith, a cylinder adapted to coact with eachof said compressor pistons, the outer end of each of said last mentionedcylinders being closed so as to form, with the outer face of thecorresponding compressor piston, a pneumatic cushion chamber adapted toact as energy accumulator, a guiding tube mounted in fixed position ineach of said last mentioned cylinders, parallel to and at a distancefrom the axis thereof, said tube extending with a snug fit through thecorresponding compressor piston and opening into the correspondingenergy accumulator chamber, and tube means for interconnecting the openends of said guiding tubes located on the other sides from said chamberswith respect to said compressor pistons, respectively.

2. A free piston machine which comprises, in combination, a motorcylinder, two freely movable motor pistons adapted to work in opposeddirections in synchronism with each other in said cylinder, a compressorpiston rigid with each of said motor pistons on the outer side thereofand in coaxial relation therewith, a cylinder adapted to coact with eachof said compressor pistons, the outer end of each of said last mentionedcylinders being closed so as to form, with the outer face of thecorresponding compressor piston, a pneumatic cushion chamber adapted toact as energy accumulator, a guiding tube mounted in fixed position ineach of said last mentioned cylinders, parallel to and at a distancefrom the axis thereof, said tube extending with a snug fit through thecorresponding compressor piston and opening into the correspondingenergy accumulator chamber, a compressed air feed reservoir for saidmotor cylinder surrounding the latter, and tube means in said reservoirfor interconnecting the open ends of said guiding tubes located on theother sides from said chambers with respect to said compressor pistons,respectively.

3. A free piston machine which comprises, in combination, a motorcylinder, at least one freely movable motor piston in said cylinder, atleast one compressor piston rigid with said motor piston coaxiallytherewith, a cylinder adapted to 'coact with said compressor piston, aguiding rod mounted in fixed position in said last mentioned cylinder,parallel to and at a distance from the axis thereof, said rod extendingwith a snug sliding fit through said compressor piston, an axial guidingrod carried by the outer end of said second mentioned cylinder, the unitformed by said two pistons being provided with an axial housing forslidably accommodating said last mentioned rod, and a pivot jointinterposed between said axial rod and a portion of said unit.

4. A free piston machine which comprises, in combination, a motorcylinder, at least one freely movable motor piston in said cylinder, acompressor piston rigid with said motor piston on the outer side thereofand in coaxial relation therewith, a cylinder adapted to coact with saidcompressor piston, an axial tubular rod carried by the second mentionedcylinder and extending inwardly toward said motor cylinder, saidcompressor and motor pistons being provided with an axial housing foraccommodating said rod, the end of said motor piston being provided witha recess, an axial sleeve carried by said motor piston inside saidhousing and communicating at one end with said recess, the other end ofsaid sleeve being slidable with a fiuidtight fit on the inner end ofsaid tubular rod, and a conduit extending axially in said tubular rodand said sleeve, with an annular clearance around it, for circulation ofa cooling liquid stream through said conduit, said recess of the motorpiston and the annular interval between said conduit and said rod andsleeve.

5. A free piston machine which comprises, in combination, a motorcylinder, at least one freely movable motor piston in said cylinderincluding a central portion and at least one peripheral cylindricalportion axially guided in said cylinder, a pivot joint between theperipheral and central portions of said motor piston, at least onecompressor piston, on the outer side of said motor piston, rigid withsaid central portion thereof in coaxial relation with said centralportion, and a compressor cylinder adapted to cooperate with axiallyguiding the unit formed by said two pistons with respect to saidcompressor cylinder, said last mentioned means including an axial rodcarried by said compressor cylinder extending toward said motorcylinder, a part slidable along said rod, and a pivot joint between saidpart and said unit, and a fixed guiding rod parallel to and at adistance from the axis of said compressor piston, said last mentionedrod extending with a snug sliding fit through said compressor piston.

7. A free piston machine which comprises, in combination, a motorcylinder, at least one freely movable motor piston in said cylinder, atleast one compressor piston rigid with said motor piston and providedwith at least one eccentric longitudinal passage extending throughoutits length, a cylinder adapted to coact with said compressor piston, atleast one guiding rod fixed to said last mentioned cylinder, parallel toand at a distance from the axis thereof, extending through said passage,a tubular member arranged to fit snugly on said rod in said passage,said member having plane walls parallel to the axial plane of thecompressor piston that passes through the axis of said tubular member,an end plate secured to said piston and provided with extensions havinginner plane walls adapted to cooperate with said plane walls of thetubular member for the radial guiding of said member with respect tosaid compressor piston, and packing means in said passage adapted tocooperate with said rod.

HEDGE BODVAR HORGEN'.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,747,948 Pescara Feb. 18, 19302,028,331 Janicke Jan. 21, 1936 2,077,802 Martin Apr. 20, 193"!2,178,310 Pescara Oct. 31, 1939 FOREIGN PATENTS Number Country Date426,693 Great Britain Apr. 8, 1935 770,023 France June 18, 1934

